Capacitive touchpad is widely used for the pointing device in a computer system. A capacitive touchpad typically has a large number of scan lines connected from the controller chip of the touchpad to a group of X trances and a group of Y trances that are arranged to have a matrix of intersections each between one X trace and one Y trace, and detects the position on a panel of the touchpad that is touched by an object such as finger or conductor by detecting the capacitance change at the intersection corresponding to the touched position. The conventional capacitive touchpad could further determine the distance and speed of a movement of the object slipping on the panel upon the variations of the touched position.
To connect with scan lines, the controller chip of a conventional capacitive touchpad is requested to have a large number of pins each for one of the scan lines. In other words, the number of the pins for the scan lines is the same as the number of the scan lines. As the number of the scan lines increases, the number of the pins on a controller chip of a conventional capacitive touchpad increases accordingly, and the related circuit in the controller is also enlarged. As a result, the chip size and the cost of the fabrication as well as the package for the controller chip increase. Moreover, in the operations of a capacitive touchpad, the more the scan lines the touchpad has, the more power the controller thereof consumes.
Therefore, it is desired a simplified capacitive touchpad with lower cost and power consumption.